This invention relates to a system comprising a method and apparatus for crystallization of polymers, particularly polyesters. Several prior art systems involving both mechanical and pneumatically agitated vessels have been traditionally used to process homopolymers; however, where copolymers are involved, traditional crystallizers do not provide desired efficiencies from the standpoint of cost and ease of operations.
Pneumatically agitated systems, that is systems employing a fluidized bed, have capacities in excess of three tons per hour; however, there is a high tendency in such systems for material chips to stick together. Furthermore, such systems involve high energy consumption which increases the difficulty in operating the system.
Mechanically agitated systems, that is systems using mixers with heat exchange capacities, have involved excess generation of fines. In addition, it is difficult to achieve high production rates since long residence times for crystallization are required in such mechanical systems. Prior art systems of the mechanical type which have been developed for polymer crystallization are disclosed in Halek, et al. U.S. Pat. No. 4,223,128 and Herron U.S. Pat. No. 4,161,578.